Q.

If one root of the quadratic equation ix2-2i+1x+2-i=0, i=-1 is 2-i, the other root is

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a

2+i

b

2-i

c

-i

d

i

answer is A.

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Detailed Solution

Given quadratic equation is

 ix2-2i+1x+2-i=0    Let  i=-1  i2=-1

And, one given root is 2-i.

We have to find the other root.

Using the fact of quadratic equation ax2+bx+c=0 that

Sum of roots =-ba

and product of roots =ca

So, for the given quadratic equation,

Sum of roots=--2i+1i                          b=-2i+1a=i                       =2i+1i=2i+1i×ii         Rationalising                       =2i2+ii2=2-1+i-i            i2=-1                       =21-i=2-2i

Given one root is 2-i

So, the other root of the given quadratic equation is sum of roots minus one root value.

Other root=Sum of roots-Given one root                       =2-2i-2-i                       =2-2i-2+i=-i  

So, the other root is -i.

Hence, option 1 is correct.

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